Food

import java.io.*;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 *
 * @author guest-kidtfF
 */
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        List<Friend> friends = new ArrayList<>();
        IO io = new IO();
        final int max = io.nextInt();
        for(int i = 0; i < max; i++) {
            long c = io.nextLong();
            long d = io.nextLong();
            friends.add(new Friend(c, d));
        }
        Collections.sort(friends);
        long roll = 0;
        long total = 0;
        if(friends.size() == 1) {
            System.out.println(friends.get(0).getCallTime() + friends.get(0).getDeliveryTime());
            System.exit(0);
        }
        /*for(Friend f : friends) {
            if(roll == 0) {
                total += f.getDeliveryTime();
                roll = f.getDeliveryTime();
            } else {
                roll -= f.getDeliveryTime();
            }
            roll -= f.getCallTime();
            if(roll < 0) {
                total += Math.abs(roll);
                roll = 0;
            }
        }*/
        //hc koodi alkaa taas täst
        long time=0;
        long boobs=0;   //hc muuttuja
        for(Friend f : friends) {
            time += f.getCallTime();
            if(boobs < f.getDeliveryTime() + time) {
                boobs = f.getDeliveryTime() + time;
            }
        }
        
        System.out.println(boobs);
    }
    
    private static class Friend implements Comparable<Friend> {
        
        private long callTime;
        private long deliverytime;
        
        public Friend(long callTime, long deliverytime) {
            this.callTime = callTime;
            this.deliverytime = deliverytime;
        }
        
        public long getDeliveryTime() {
            return deliverytime;
        }
        
        public long getCallTime() {
            return callTime;
        }
        
        @Override
        public String toString() {
            return callTime + ", " + deliverytime;
        }

        @Override
        public int compareTo(Friend o) {
            if(o.getDeliveryTime() == getDeliveryTime()) {
                return o.getCallTime() > getCallTime() ? (o.getCallTime() == getCallTime() ? 0 : -1) : 1;
            }
            return o.getDeliveryTime() > getDeliveryTime() ? 1 : -1;
        }
    }

    public static class IO extends PrintWriter {
	private InputStreamReader r;
	private static final int BUFSIZE = 1 << 15;
	private char[] buf;
	private int bufc;
	private int bufi;
	private StringBuilder sb;
	
	public IO() {
		super(new BufferedOutputStream(System.out));
		r = new InputStreamReader(System.in);
		
		buf = new char[BUFSIZE];
		bufc = 0;
		bufi = 0;
		sb = new StringBuilder();
	}
	
	private void fillBuf() throws IOException {
		bufi = 0;
		bufc = 0;
		while(bufc == 0) {
			bufc = r.read(buf, 0, BUFSIZE);
			if(bufc == -1) {
				bufc = 0;
				return;
			}
		}
	}
	
	private boolean pumpBuf() throws IOException {
		if(bufi == bufc) {
			fillBuf();
		}
		return bufc != 0;
	}
	
	private boolean isDelimiter(char c) {
		return c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '\f';
	}
	
	private void eatDelimiters() throws IOException {
		while(true) {
			if(bufi == bufc) {
				fillBuf();
				if(bufc == 0) throw new RuntimeException("IO: Out of input.");
			}
			
			if(!isDelimiter(buf[bufi])) break;
			++bufi;
		}
	}
	
	public String next() {
		try {
			sb.setLength(0);
			
			eatDelimiters();
			int start = bufi;
			
			while(true) {
				if(bufi == bufc) {
					sb.append(buf, start, bufi - start);
					fillBuf();
					start = 0;
					if(bufc == 0) break;
				}
				
				if(isDelimiter(buf[bufi])) break;
				++bufi;
			}
			
			sb.append(buf, start, bufi - start);
			
			return sb.toString();
		} catch(IOException e) {
			throw new RuntimeException("IO.next: Caught IOException.");
		}
	}
	
	public int nextInt() {
		try {
			int ret = 0;
			
			eatDelimiters();
			
			boolean positive = true;
			if(buf[bufi] == '-') {
				++bufi;
				if(!pumpBuf()) throw new RuntimeException("IO.nextInt: Invalid int.");
				positive = false;
			}
			
			boolean first = true;
			while(true) {
				if(!pumpBuf()) break;
				if(isDelimiter(buf[bufi])) {
					if(first) throw new RuntimeException("IO.nextInt: Invalid int.");
					break;
				}
				first = false;
				
				if(buf[bufi] >= '0' && buf[bufi] <= '9') {
					if(ret < -214748364) throw new RuntimeException("IO.nextInt: Invalid int.");
					ret *= 10;
					ret -= (int)(buf[bufi] - '0');
					if(ret > 0) throw new RuntimeException("IO.nextInt: Invalid int.");
				} else {
					throw new RuntimeException("IO.nextInt: Invalid int.");
				}
				
				++bufi;
			}
			
			if(positive) {
				if(ret == -2147483648) throw new RuntimeException("IO.nextInt: Invalid int.");
				ret = -ret;
			}
			
			return ret;
		} catch(IOException e) {
			throw new RuntimeException("IO.nextInt: Caught IOException.");
		}
	}
	
	public long nextLong() {
		try {
			long ret = 0;
			
			eatDelimiters();
			
			boolean positive = true;
			if(buf[bufi] == '-') {
				++bufi;
				if(!pumpBuf()) throw new RuntimeException("IO.nextLong: Invalid long.");
				positive = false;
			}
			
			boolean first = true;
			while(true) {
				if(!pumpBuf()) break;
				if(isDelimiter(buf[bufi])) {
					if(first) throw new RuntimeException("IO.nextLong: Invalid long.");
					break;
				}
				first = false;
				
				if(buf[bufi] >= '0' && buf[bufi] <= '9') {
					if(ret < -922337203685477580L) throw new RuntimeException("IO.nextLong: Invalid long.");
					ret *= 10;
					ret -= (long)(buf[bufi] - '0');
					if(ret > 0) throw new RuntimeException("IO.nextLong: Invalid long.");
				} else {
					throw new RuntimeException("IO.nextLong: Invalid long.");
				}
				
				++bufi;
			}
			
			if(positive) {
				if(ret == -9223372036854775808L) throw new RuntimeException("IO.nextLong: Invalid long.");
				ret = -ret;
			}
			
			return ret;
		} catch(IOException e) {
			throw new RuntimeException("IO.nextLong: Caught IOException.");
		}
	}
	
	public double nextDouble() {
		return Double.parseDouble(next());
	}
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED